The present invention relates to a system for controlling wireless communication between a portable device and a communication controller, and more particularly, to a communication control system for controlling the locking and unlocking of a vehicle door through wireless communication.
Japanese Laid-Open Patent Publication No. 2001-311333 describes a vehicle communication control system that remotely controls security equipment through wireless communication. The vehicle communication control system controls wireless communication performed between a portable device, which is held by a vehicle user, and a communication controller, which is installed in a vehicle. The communication automatically locks and unlocks a vehicle door and enables the starting of the engine.
More specifically, the communication controller transmits a request signal to a predetermined area near the vehicle and a predetermined area in the passenger compartment. When receiving the request signal from an associated communication controller, the portable device automatically returns an ID code signal, which contains a predetermined identification (ID) code set for the portable device. Then, the communication controller compares (verifies) the ID code of the ID code signal with a predetermined ID code set for the communication controller. When the two ID codes are the same, the communication controller automatically unlocks the door or enables the starting of the engine.
Disturbance such as noise may be mixed in the ID code signal transmitted from the portable device. This may modify the data of the ID code in the ID code signal. As a result, the communication controller would not be able to recognize the original ID code. Particularly, when noise is cyclically produced such that it is synchronized with the transmission cycle of the ID code signal, communication errors may continuously occur in the communication control system of the prior art. Thus, there is a need to improve the noise resistance in the communication control system of the prior art.